Software Freedom Day (SFD) is an annual worldwide celebration of free/open-source software. SFD is a public education effort, not only to celebrate the virtues of free/open-source software, but also to encourage its use, to the benefit of the public.
Software Freedom Day was established in 2004 and was first observed on August 28, 2004 when over 70 teams participated. Since that time it has grown in popularity as more than 300 teams from over 60 countries celebrated on the second SFD, held on September 10, 2005. In 2008, over 500 teams in over 90 countries all around the world celebrated the SFD. The primary sponsor for 2005-2006 was Canonical Ltd., the company behind Ubuntu, a Linux distribution.
Here are some useful links:
Linux a Parco Città: Settimana del software libero - Gruppo Utenti GNU/Linux Vicenza